1/4 inch is one heck of a warp in a piece that is meant to be relatively flat to start. The dihedral brace build I described in my earlier post really is hard at all with a little patience. And, if you're not satisfied with the first...cut out another.....before gluing of course. The wood is cheap. A severely warped piece has to be custom shaped(sanded) for each half of it. If the whole thing is flat to start, just makes the rest easier. After all, this is one of the really critical joints in the plane.